Bass amp thumping noise

[Indy]

Hello there, i'm wondering if anyone could help me here, you'll have to be patient as i'm going to explain this the simplest way I can, I'm not the most technically minded.

What I have:

A peavey Data Bass head 550 watt plug, and a lead that leads to a:

Audio tec speaker cab, the lead feeds into one of two inputs in the rear of cab.

inside the Cab is the two inputs that are connected to each other on the inside, then from the inputs is a positive and negative wire that is connected to an Eminence Speaker.

The problem:

When i turn the amp on a get a dull thud that repeats every second, i cannot get any sound from the amp at all, although it was working fine yesterday. Just a dull thud-thud-thud.

I have no idea how the amp works (I apologise), I don't know why there is even two inputs on the cab and not one!! Would anybody be able to tell me what the problem may be?

I would be very very grateful

Thanks in advance

Will

[Norris]

I'm sure my Databass combo thumped when you turn it on, but just the once. Mine did have a habit of blowing fuses when switched on until it was modded with a capacitor across the main power lines.

Sorry, that's probably not much help

[Norris]

... unless yours has had a similar mod done and the capacitor is knackered

[Indy]

Thanks for the response, yeah it used to do thus once when turned on and then work normal. Now it's just a thud every second!

[icastle]

There are two inputs on the cab so you daisy chain out of the first cab into a second one.

As for the evenly spaced 'thuds' thats most likely a duff electrolytic capacitor, probably around the power supply area of the board.

I get the impression that you are to electronics what I am to male modelling, so an amp tech is probably your best bet with that.

[Indy]

You would be correct, useless! Thank you for the response. I'll take it to someone who knows what they're doing.

Thanks

[icastle]

[quote name='Indy' timestamp='1459368717' post='3015955']
You would be correct, useless! Thank you for the response. I'll take it to someone who knows what they're doing.

Thanks
[/quote]

No problem Indy.
In the meantime I promise to stay off the catwalk.

[GOM]

Those "thuds" are definitely something wrong with the amp ... it used to be called "motor boating" - no idea why - as Icastle said the most likely cause is the power supply coming up, overloading, going down and then repeating ad nausiam. Get it looked at by a tech.

[Happy Jack]

Unless your amp has a 'metronome' setting, of course ...

[Twincam]

[quote name='GOM' timestamp='1459434249' post='3016557']
Those "thuds" are definitely something wrong with the amp ... it used to be called "motor boating" - no idea why - as Icastle said the most likely cause is the power supply coming up, overloading, going down and then repeating ad nausiam. Get it looked at by a tech.
[/quote]

Motor boating is a term used for valve amps and describes a type of feedback that manifest as oscillations that sound like a old slow boat engine.

[SICbass]

Motor boating meant something entirely different when I was a teenager 😏

Edited April 1, 2016 by SICbass

[Indy]

Taking it in on Monday to someone in the know. Thanks for all posts. Motorboating is still something my misses won't do!